Not really answering your question but I have a book called "Neolithic Dew-ponds and CattleWays" 1907, which shows dewponds at several hill forts in this area, though not Figsbury, the Cissbury and Maiden Castle dewponds are particularly good.
As a book its completely up the creek, but it does show that we should'nt interpret stones, dips in the ground, always from an earlier period.
He has wolf platforms guarding the settlement up on Martinsell Hill, Oare, he thinks they are to guard against wolves attacking the fort, but I'd rather see a pair of wolves sitting quietly on their platforms surveying the Wiltshire scene.

Dewponds on chalk; puddled clay, beaten down to form an impermeable layer in which (I don't know) the early morning dew condensed to form ponds - found on the Wiltshire downs....